Tailor-Made Synthesis of Hydrosilanols, Hydrosiloxanes, and Silanediols Catalyzed by di-Silyl Rhodium(III) and Iridium(III) Complexes

Siloxanes and silanols containing Si–H units are important building blocks for the synthesis of functionalized siloxane materials, and their synthesis is a current challenge. Herein, we report the selective synthesis of hydrosilanols, hydrosiloxanes, and silanodiols depending on the nature of the catalysts and the silane used. Two neutral ({MCl[SiMe2(o-C6H4PPh2)]2}; M = Rh, Ir) and two cationic ({M[SiMe2(o-C6H4PPh2)]2(NCMe)}[BArF4]; M = Rh, Ir) have been synthesized and their catalytic behavior toward hydrolysis of secondary silanes has been described. Using the iridium complexes as precatalysts and diphenylsilane as a substrate, the product obtained is diphenylsilanediol. When rhodium complexes are used as precatalysts, it is possible to selectively obtain silanediol, hydrosilanol, and hydrosiloxane depending on the catalysts (neutral or cationic) and the silane substituents.


Catalytic hydrolysis of diphenylsilane
Reaction Conditions: An initial set of experiments were conducted to optimize catalyst and water concentrations with constant amounts of diphenylsilane (0.22 mmol) and solvent (THF,1mL).S-5

Recyclability of 1[BAr F 4]
The recyclability of 1[BAr F 4] was studied using Man on the Moon system, measuring H2 gas pressure.In an inert atmosphere of nitrogen, 0.2 mol% of catalyst and 100 equivalents of distilled water were solved in 1 mL of distilled THF. 10 reaction cycles were done by sequentially adding 40 µL of diphenylsilane and restoring the initial pressure.S-18

Hydrolysis and alcoholysis of other silanes
Alcoholysis of diphenylsilane: A closed reaction vessel equipped with a pressure transducer (Manonthemoon kinetic kit X102) was immersed in a thermostated ethylene glycol/water bath and charged with 1[BAr F 4] (0.00044 mmol) in 1 mL of distilled THF and R-OH (2.2 mmol).Once the pressure of the system was stabilized, the silane (0.22 mmol) was added, which was considered initial reaction time.The solution was left stirring until the pressure stabilized again, which was indicative that the reaction ended.

Hydrolysis of other silanes:
A closed reaction vessel equipped with a pressure transducer (Manonthemoon kinetic kit X102) was immersed in a thermostated ethylene glycol/water bath and charged with 1[BAr F 4] (0.00044 mmol) in 1 mL of distilled THF and H2O (2.2 mmol).Once the pressure of the system was stabilized, the silane (0.22 mmol) was added, which was considered initial reaction time.The solution was left stirring until the pressure stabilized again, which was indicative that the reaction ended.

X-ray crystallography tables
S-20

Figure S. 5
Figure S.5. 1 H NMR array of the reaction of dihenylsilane with water in the presence of 0.2 mol% of 2[BAr F 4] and time-correlated speciation diagram.

Figure
Figure S.8.Hydrolysis of diphenylsilane with 1[BAr F 4] at extended reaction times.

Figure
Figure S.14. 1 H NMR of hydrolysis of naphthylphenylsilane catalyzed by 1.

Figure S. 25 .
Figure S.25.Reactions involved in the formation of the different Si-O products found in this work.In black, identified and characterized products; in grey, potential polysiloxanes found in the reaction of dihydrosilanes with 1 and 1[BAr F 4] at long reaction times; in red, nucleophilic attack of silanol to hydrosilanes (not observed).

Table S . 1 .
Optimization of the catalyst and water concentration in the hydrolysis of diphenylsilane Figure S.1. 1H NMR of hydrolysis of diphenylsilane catalyzed by 1.

Table S .
4. Crystallographic data and structure refinement details of all compounds.